A mouse aging contract was initiated with Jackson Laboratories to provide side-by-side cohorts of 2, 10 and 20 month old mice. The first two sets have been delivered. One set was injected with murine 4T1-luciferase mammary cells in the mfp, which were resected after primary tumor formation, with lung and liver metastases as an endpoint. The other set used 6DT1/MVT1 mammary tumor cells in a similar experiment. In both cases, no difference in primary tumor size was noted; metastasis endpoints are ongoing. Additional model systems to embrace the heterogeneity of triple-negative breast cancer, and different metastasis endpoints (lung, liver, brain) are planned.